This invention relates to the manufacture of soluble coffee and more particularly to a process for treating insolubles obtained from soluble coffee extract to render them soluble and thus provide higher yields for the overall process.
In the manufacture of soluble coffee, coffee extracts are obtained by contacting the coffee material with an extraction medium so as to extract soluble solids. For example, percolation techniques are normally employed to extract soluble solids from roasted and ground coffee on a commercial scale.
The coffee extracts obtained from such extraction processes generally contain considerable amounts of material which is relatively insoluble except in high temperature mediums. In the manufacture of coffee extracts, the insolubles may contain hydrolysis products produced during the later stages of percolation, some roasted and ground coffee fines carried off by the extract, and other insoluble complexes. Though some of these insolubles are soluble to a degree in heated mediums, these insolubles present particular problems when drying methods such as low-temperatures spray-drying or freeze-drying are employed, methods necessitating cooling of the coffee extract. It is generally a common practice to remove these insolubles to avoid plugging problems in the various pieces of processing equipment and also the appearance of "specks" of insoluble material in the eventually reconstituted product. Since coffee extract will generally be associated with the insolubles which are to be removed, centrifuging is a preferred separation method since it effectively separates a substantial amount of extract liquid from the insolubles.
In the soluble coffee process, the removal of these insoluble materials is, in effect, a removal of coffee solids and, hence, results in the waste of desirable constituents. In some cases, a loss of 10% coffee solids has been noted. Further, certain of the constituents comprising the insoluble matter may impart and contribute to desirable organoleptic properties in the reconstituted beverage.
Accordingly, it is an object of this invention to treat the insolubles found in extracts of coffee to enable their use in the final coffee product.
Other objects will become apparent upon reading the specification and claims which follow.